using System.Numerics;
using AcDream.App.Rendering;
using AcDream.App.Rendering.Gpu;

namespace AcDream.App.Tests.Rendering;

public sealed class RetailDetailTextureContractTests
{
    private static readonly TerrainAtlas.RetailDetailTextureBinding Available = new(
        new GpuTextureSlot(7),
        Tiling: 4f,
        SurfaceTextureId: 0x05001787,
        RenderSurfaceId: 0x06006D58,
        Width: 256,
        Height: 256);

    [Fact]
    public void ExistingBuildingDetailSettingIsTheLivePassGate()
    {
        Assert.False(RetailDetailTextureContract.ShouldRender(false, Available));
        Assert.True(RetailDetailTextureContract.ShouldRender(true, Available));
        Assert.False(RetailDetailTextureContract.ShouldRender(true, default));
    }

    [Fact]
    public void OpaqueDetailUsesDepthEqualityWhileTransparentDetailDoesNot()
    {
        Assert.Equal(
            GpuCompareOp.Equal,
            RetailDetailTextureContract.DetailDepthCompare(transparent: false));
        Assert.Equal(
            GpuCompareOp.LessOrEqual,
            RetailDetailTextureContract.DetailDepthCompare(transparent: true));
    }

    [Theory]
    [InlineData(0f, 1f)]
    [InlineData(10f, 1f)]
    [InlineData(30f, 0.5f)]
    [InlineData(50f, 0f)]
    [InlineData(80f, 0f)]
    public void DistanceFadeUsesPositiveViewDepthInMetres(
        float depthMetres,
        float expected)
    {
        Assert.Equal(
            expected,
            RetailDetailTextureContract.FadeForPositiveViewDepthMetres(depthMetres),
            precision: 5);
    }

    [Fact]
    public void FadeZeroIsExactNoOpAndNeutralRgbEqualsAlpha()
    {
        var brighteningSample = new Vector4(0.459f, 0.459f, 0.459f, 0.282f);
        Assert.Equal(
            Vector3.One,
            RetailDetailTextureContract.FramebufferFactor(brighteningSample, fade: 0f));

        var neutral = new Vector4(0.4f, 0.4f, 0.4f, 0.4f);
        Vector3 neutralFactor = RetailDetailTextureContract.FramebufferFactor(neutral, fade: 1f);
        Assert.Equal(1f, neutralFactor.X, precision: 5);
        Assert.Equal(1f, neutralFactor.Y, precision: 5);
        Assert.Equal(1f, neutralFactor.Z, precision: 5);
    }

    [Fact]
    public void RetailBlendPreservesMeasuredBrightening()
    {
        var measured = new Vector4(0.459f, 0.459f, 0.459f, 0.282f);
        Vector3 factor = RetailDetailTextureContract.FramebufferFactor(measured, fade: 1f);

        Assert.Equal(1.177f, factor.X, precision: 5);
        Assert.Equal(1.177f, factor.Y, precision: 5);
        Assert.Equal(1.177f, factor.Z, precision: 5);
    }

    [Fact]
    public void EnabledDerethCategoryTextureKeepsItsMeasuredBrightening()
    {
        var derethCategory = new Vector4(0.165f, 0.165f, 0.165f, 0.132f);
        Vector3 factor = RetailDetailTextureContract.FramebufferFactor(
            derethCategory,
            fade: 1f);

        Assert.Equal(1.033f, factor.X, precision: 5);
        Assert.Equal(1.033f, factor.Y, precision: 5);
        Assert.Equal(1.033f, factor.Z, precision: 5);
    }
}